Field of the Invention
The present invention relates to a transmission X-ray generating tube, an X-ray generating apparatus, and an X-ray imaging system with an anode, and an anode used therefor, the anode including a target for generating an X-ray through irradiation of an electron beam and a tubular anode member with an opening for holding the target.
Description of the Related Art
A transmission X-ray generating tube including a transmission target is known. The transmission target uses an X-ray emitted from a side thereof, which is opposite to a side, on which an electron beam enters the target. The transmission X-ray generating tube may include a target made of diamond as an end window of the X-ray generating tube. Such a transmission X-ray generating tube has advantageous features in that a radiation angle can become wider, heat dissipation performance can become higher, and an X-ray generating apparatus can be downsized. The target in such a transmission X-ray generating tube is hermetically bonded to an anode member via a bonding material such as a silver brazing material, an Ag—Sn based brazing material, or an Au—Sn based brazing material formed on a periphery of the target. Such a brazing material is adopted that has a melting point of from 200° C. to a temperature of the anode member when operated or higher. When the Ag—Sn based brazing material is used, by controlling composition ratios therein or using a ternary or higher brazing material, material design of a wide range of melting points is possible (100° C. to 900° C.)
In Japanese Patent Application Laid-Open No. 2013-51153, there is disclosed a transmission X-ray generating tube including a tubular anode member having opening diameter with a distribution and a transmission target held by the anode member. Further, in Japanese Patent Application Laid-Open No. 2013-55041, there is disclosed an X-ray generating tube including a tubular anode member formed of a member having a high X-ray blocking property and a thermally conductive member, and a transmission target held by the anode member. In such an X-ray generating tube including the transmission target as an end window, when X-ray generating operation is repeated, a desired tube current sometimes cannot be obtained and hence it is difficult to secure a necessary X-ray output. A transmission X-ray generating tube that can obtain a stable X-ray output has been required.